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Título: | Metabolic and ionoregulatory responses of the Amazonian cichlid, Astronotus ocellatus, to severe hypoxia |
Autor: | Richards, Jeffrey G. Wang, Yuxiang S. Brauner, Colin John Gonzalez, Richard J. Patrick, Marjorie L. Schulte, Patricia Choppari-Gomes, A. R. Val, Vera Maria Fonseca Almeida e Val, Adalberto Luis |
Palavras-chave: | Adenosine Triphosphatase (potassium Sodium) Adenosine Triphosphate Creatine Creatine Phosphate Glycogen Hemoglobin Ion Lactate Dehydrogenase Lactic Acid Rna, Messenger Oxygen Pyruvate Dehydrogenase Complex Pyruvic Acid Adaptation Animals Anoxia Blood Cichlid Enzymology Fast Muscle Fiber Genetics Gill Glucose Blood Level Hematocrit Kidney Liver Mean Corpuscular Volume Metabolism Pathophysiology Ph Physiology Adaptation, Physiological Adenosine Triphosphate Animal Anoxia Blood Glucose Cichlids Creatine Erythrocyte Indices Gills Glycogen Hematocrit Hemoglobins Hydrogen-ion Concentration Ions Kidney L-lactate Dehydrogenase Lactic Acid Liver Muscle Fibers, Fast-twitch Oxygen Phosphocreatine Pyruvate Dehydrogenase Complex Pyruvic Acid Rna, Messenger Sodium-potassium-exchanging Atpase Astronotus Ocellatus Cichlidae |
Data do documento: | 2007 |
Revista: | Journal of Comparative Physiology B: Biochemical, Systemic, and Environmental Physiology |
É parte de: | Volume 177, Número 3, Pags. 361-374 |
Abstract: | We examined the metabolic and ionoregulatory responses of the Amazonian cichlid, Astronotus ocellatus, to 20 h exposure to severe hypoxia (0.37 ± 0.19 mg O2/l; 4.6% air saturation) or 8 h severe hypoxia followed by 12 h recovery in normoxic water. During 20 h exposure to hypoxia, white muscle [ATP] was maintained at normoxic levels primarily through a 20% decrease in [creatine phosphate] (CrP) and an activation of glycolysis yielding lactate accumulation. Muscle lactate accumulation maintained cytoplasmic redox state ([NAD+]/[NADH]) and was associated with an inactivation of the mitochondrial enzyme pyruvate dehydrogenase (PDH). The inactivation of PDH was not associated with significant changes in cytoplasmic allosteric modulators ([ADPfree], redox state, or [pyruvate]). Hypoxia exposure caused a ∼65% decrease in gill Na+/K+ ATPase activity, which was not matched by changes in Na+/K+ ATPase α-subunit protein abundance indicating post-translational modification of Na+/K+ ATPase was responsible for the decrease in activity. Despite decreases in gill Na+/K+ ATPase activity, plasma [Na+] increased, but this increase was possibly due to a significant hemoconcentration and fluid shift out of the extracellular space. Hypoxia caused an increase in Na+/K+ ATPase α-subunit mRNA abundance pointing to either reduced mRNA degradation during exposure to hypoxia or enhanced expression of Na+/K + ATPase α-subunit relative to other genes. © 2007 Springer-Verlag. |
DOI: | 10.1007/s00360-006-0135-2 |
Aparece nas coleções: | Artigos |
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